The invention relates to brachytherapy devices for implanting radioactive seeds into a patient""s body for treatment of cancer. More specifically, the invention relates to a needle with an aperture on the shaft that permits visual inspection of a sequence of radioactive seeds and spacers loaded into the needle. In addition, the invention relates to seeds or spacers that are colored to facilitate visual detection of the same when loaded into a brachytherapy device.
Brachytherapy is a cancer treatment regiment that includes interstitial implanting of radioactive seeds directly into tumors in a patient""s body. Brachytherapy is particularly suitable for localized tumors that can be directly reached using needles and catheters. Treatment of prostate cancer is an example of condition where brachytherapy is a preferred procedure. According to the American Cancer Society, upwards of 180,000 men in the United States will be diagnosed with prostate cancer each year. Prostate treatment options typically have included radical prostatectomy (removal of the prostate) and external beam radiation. Both these methods result in unwanted destruction of non-tumorgenic tissue with corresponding adverse side-effects. The newer brachytherapy method involves permanently implanting tiny radioactive xe2x80x9cseedsxe2x80x9d directly into the prostate to kill cancer cells. This is becoming the treatment of choice because the radiation is concentrated in the affected area and avoids many of the side-effects associated with other treatment methods, including incontinence, impotence and hormonal imbalance. Current estimates show that over 25% of prostate cancer patients will choose prostate brachytherapy (radioactive seed implants) or other seed implant procedures, and this number is expected to rise as techniques and equipment used for the procedure improve.
The success of a seed implant therapy depends greatly on the precise placement of the seeds within the tissue containing the tumor. This is particularly true in tumors located in tissues with closely associated structures that could be damaged by improper implantation. For example, in the case of prostate cancer, the physician must be able to insert the seeds without interfering with the urethra (which goes through the prostate) or the rectum (which is below the prostate) while ensuring that the proper radiation dosage is being delivered to the entire prostate. To facilitate proper localization of the tumor and proper procedure for implanting seeds, a dosimetrist will use a computer system to prepare treatment xe2x80x9cmapsxe2x80x9d by using images taken from a transrectal ultrasound study to determine the best placement for the seeds so as to deliver an optimal dose of radiation. For a typical treatment plan in prostate cancer, an average of 120 seeds will be prescribed and 20-25 needles will be used in a three-dimensional array to implant the seeds at proper locations determined according to the treatment maps. The treatment plan typically includes instructions for what needles are to be inserted into which position in the tumor, and how many seeds are to be loaded into each needle according to a precise spacing pattern that corresponds to the implant locations determined by the map. The spacing pattern in the needle is set by alternatively loading a radioactive seed or a non-radioactive spacer in a particular load sequence. For optimal therapeutic benefit without adverse side-effects, it is essential that the needles have the correct load sequence of seeds and spacers determined according to the treatment plan.
However, the current needles and brachytherapy devices used for implanting seeds and spacers do not allow the person using the device to detect and confirm the load sequence of seeds and spacers after they have been loaded into the device. Improper loading can lead to a deviation from the treatment plan and cause areas to be treated with too much radiation or too little radiation in particular spots. This is especially true when the area around the urethra or other parts is implanted, because improper implanting may cause loose seeds to migrate into the urethra increasing the probability that seeds may be expelled and/or result in acute/long-term side-effects.
Current device loading practice dictates that if a technician is manually loading seeds or spacers into the device and cannot confirm correct placement of a seed or a spacer, the technician must empty the device and begin again. This safety practice can result in substantially increased cost in providing brachytherapy applications. Operating room costs in the U.S. typically are in the range of $25-75 per minute. Unloading and reloading a device can take several minutes to complete. Therefore, a mistake, if discovered, can quickly add large and unnecessary expense to a brachytherapy procedure. If undiscovered, it can result in hot spots or cold spots as a result of too much or not enough radiation being provided.
Accordingly, there is a need in the art to lessen the problems associated with an improperly loaded brachytherapy device by facilitating detection of the load sequence of seeds and spacers used therein. The present invention is directed to this need.
In one aspect, there is provided, a device for implanting radioactive seeds and spacers into tissue that includes, a shaft enclosing an interior space for receiving a load sequence of seeds and spacers. The shaft contains an aperture positioned along a portion of the shaft that exposes a sufficient portion of the interior space to allow the load sequence of seeds and spacers to be detected after the load has been received into the shaft. In one embodiment, the aperture is a slit down the longitudinal axis of the shaft, the seeds are radioactive seeds used in brachytherapy applications, and the brachytherapy is used for treatment of prostate cancer. The shaft may be a needle for direct insertion of the load of seeds and spacers, or can be a sleeve member subsequently received into another member such as a needle or catheter for implanting the load of radioactive seeds and spacers.
In another aspect, there is provided, colored seeds or spacers that facilitate direct visual detection of the load sequence of seeds and spacers in any brachytherapy application. In this regard, the invention provides a seed for implanting into tissue in a load sequence with a spacer, wherein the seed is colored with a biologically acceptable dye to identify the seed. It also provides a spacer for implanting into tissue in a load sequence with a radioactive seed, wherein the spacer is colored with a biologically acceptable dye to identify the spacer. More specifically, this aspect provides a system for detecting a load sequence of seeds and spacers in a loading shaft, wherein at least one of the seeds or spacers is colored with a biologically acceptable dye to provide an identifying color that distinguishes the seeds from the spacers. In certain embodiments, the seeds,, the spacers or both are colored. The coloration of the seeds or spacers may be according to criteria such as isotope type, material type, dose, assay date or manufacturer to help facilitate confirmation of the proper load sequence.
In related aspects, there are provided, methods for detecting a load sequence of seeds and spacers in a brachytherapy device that includes use of the aforementioned devices and systems, and/or the colored seeds and/or spacers. These include methods using both the aperture containing shaft and the colored spacers or seeds to facilitate confirmation of the load sequence of radioactive seeds and spacers in brachytherapy applications. The benefits of these and other aspects of these methods, systems and devices will be apparent to one of ordinary skill in the art in light of the following description and accompanying figures.